At the tail end of November, Left Hand Brewing filed a lawsuit against White Labs, Inc. alleging the prominent yeast supplier was responsible for a widespread contamination that led to a multi-million dollar product recall. In the suit, Left Hand charges that contaminated yeast sold by White Labs last year infected a number of beers with the Saccharomyces cerevisiae variant Diastaticus, a wild yeast strain known to cause secondary fermentation.

Reached by GBH at the time, White Labs denied culpability, saying, in part, that there was “no specific proof on where the contamination originated from,” adding “every batch of yeast is tested to confirm it is contamination free prior to shipping.”

The suit here is ultimately between two companies. But more broadly speaking, it may also serve to shine a light on a more widespread conflict, one irrespective of any individual supplier, between beer makers and the microbiology behind the very act of brewing. In fact, some are suggesting that problems with Diastaticus in particular have been gaining momentum as a serious threat to the industry at large.

“It’s definitely an issue that has affected breweries across the country,” says Andrew Gierczak, founder and brewer at MobCraft, a Wisconsin outfit that recently dealt with Diastaticus issues of its own. “It’s fairly widespread.”

How widespread those issues are would be difficult to pin down. But Left Hand isn’t the only one to go public with its woes. At the 2017 Craft Brewers Conference, Lauren Torres, lab manager at Bell’s Brewery of Michigan, conducted a talk about this particular infection under the appropriate title, “When Yeast Attack.” Similarly, Georgia’s Wild Heaven Beer tells GBH it has had problems of its own with the strain, adding a number of contemporaries in the state have dealt with the same issues. So, too, has MobCraft, as mentioned above, which posted an analysis to the Pro Brewer message board this past August detailing its own experiences.

But what makes Diastaticus so nasty compared to other contaminants? Ultimately, it’s a combination of things. For starters, more than spoiling the taste of a product, Diastaticus can lead to exploding bottles and cans, which gives it the potential to cause real injury to whoever is handling it, despite being safe to consume. In its suit, Left Hand says this happened to its own products once they reached the marketplace. Likewise, Bell’s shared pictures of exploded bottles of Winter White Ale during its CBC talk on the matter.

And while Diastaticus isn’t the only cause for exploding packaging, those with experience dealing with the strain say it’s so problematic because it’s simultaneously quite difficult to detect. That’s in part because Diastaticus has a “much lower threshold to yield problems than other organisms,” according to Gierczak, who also has a microbiology and food science background.

“This is what’s really insidious about the organism,” he says.

In addition to its detection, the growth rate of something like Diastaticus is difficult to assess. Product that’s stored cold will have very different infection results, sometimes to the point of no effect at all, compared to product stored warm on a shelf or transported across the country—or, in the case of Left Hand and other larger producers, the world.

Adds Eric Johnson, co-founder of Wild Heaven, which dumped a batch of beer a couple months ago, “Very few breweries are equipped to detect it.” And that’s true even among some of the larger breweries, as Bell’s said it “did not have great tools for detecting” Diastaticus until it was too late. The company, in turn, hired a trained microbiologist to beef up its staff.

Equally important, however, the issue seems to reveal some weak links in the supply chain. Those who spoke with GBH specified their commentary had nothing to do with Left Hand’s litigation, but agreed it’s generally difficult to prove with scientific certainty where any contamination started, even while acknowledging yeast control already plays a significant role in a brewery’s quality assurances and yeast’s tendency to drift (which is to say: evolve over time). Gierczak, for instance, says a brewer can come close to certain, but can’t reach 100% certainty unless they test the samples coming in from the supplier before use.

This poses a bit of a problem for brewers in another sense because many take it on faith that the samples they’re getting are free of contamination. In Left Hand’s lawsuit, this seems to be the critical element of their case. According to the filing, White Labs admitted to Left Hand that it “lacked the capability to test for Diastaticus,” leaving the brewery to feel further justified in challenging the yeast supplier’s warranty that all pitches of yeast it sells are contamination free.

To that end, Hunter Smith, of Champion Brewing, posted the following in a Facebook group about the issue: “One doesn’t test hops before dry-hopping either. One places trust in the supplier.” (Smith did not respond to GBH's request for comment.)

As such, this can all prove very costly, either through recalls or through investing in the resources to catch it early. Either way, there’s more at stake than the reputation of any product, to say nothing of the paramount safety of those buying said products.

“We all need to be putting out the very highest quality thing we have,” Johnson says. “Or we’re hurting the category.”